Journal of the American Chemical Society, Vol.136, No.35, 12415-12421, 2014
Facile Formation of Homoleptic Au(III) Trications via Simultaneous Oxidation and Ligand Delivery from [Phl(pyridine)(2)](2+)
We report the first examples of Au(III) tricationic complexes bound only by neutral monodentate ligands, which are a new class of gold reagents. Oxidative addition to the bis-pyridine Au(I) cation, [Au(4-DMAP)(2)](+), using a series of dicationic oxidants of the general form [PhI(L)(2)](2+) (L = pyridine, 4-DMAP, 4-cyanopyridine) allows ready access to homoleptic and pseudo-homoleptic Au(III) complexes [Au(4-DMAP)(2)(L)(2)](3+). The facile oxidative addition of Au(I) species additionally demonstrates the efficacy of PhI(L)(2)](2+) reagents as halide-free oxidants for Au(I). Comparisons are made via attempts to oxidize NHC-Au(I)Cl, where introduction of the chloride anion results in complex mixtures via ligand and chloride exchange, demonstrating the advantage of using the pyridine-based homoleptic compounds. The new Au(III) trications show intriguing reactivity with water, yielding dinuclear oxo-bridged and rare terminal Au(III)-OH complexes.